U.S. Pat. No. 4,298,025, which is owned by the present assignee, discloses a control valve for use in water softeners having two resin tanks. One of the resin tanks is normally on-line while the other tank is regenerated and placed in a standby condition until the first tank requires regeneration. The disclosed control valve controls which of the tanks is on-line and controls the regeneration sequence of an exhausted tank.
The quantity of water treated by a given tank, is monitored by a mechanism that includes a water usage turbine driven by water entering the on-line resin tank. When a predetermined quantity of water is treated, which produces to a predetermined number of revolutions in the turbine, a regeneration sequence is initiated which places the standby tank on-line and isolates the exhausted tank.
A second turbine, operatively connected to a regeneration sequence control element (in the form of a disk) is rotated by a stream of water that is activated at the beginning of the regeneration cycle. The stream of water physically drives the regeneration control disk (via the turbine and associated drive train) through its sequence. With the disclosed arrangement, the frequency of regeneration of the water softener system is determined by the usage turbine which directly measures the quantity of fluid treated by a given tank.
In U.S. Pat. No. 4,427,549 which is also owned by the present assignee, a deionization method and apparatus is disclosed. The disclosed apparatus includes a control valve similar to the control valve disclosed in U.S. Pat. No. 4,298,025 in that it includes a usage turbine for monitoring the amount of source water treated by a given tank and a regeneration control turbine for driving a control element through a regeneration sequence.
The control valves disclosed in U.S. Pat. Nos. 4,298,025 and 4,427,549 channel all water to be treated past the water usage turbine. For the valves disclosed in these patents, the flow rate is sustainable through the valve is in large measure determined by the flow rate that is sustainable through the passages conveying the water to pass the water usage turbine. Attempts have been made to improve the flow rate of the types of control valves disclosed in the above-identified patents. For example, U.S. Pat. No. 5,022,994, which is also owned by the assignee of the present invention, discloses a control valve in which the water usage turbine may be eliminated in the valve disclosed in this patent, an external triggering device is used to initiate regeneration at frequencies dependent on water usage monitored by external devices or by sensors which monitor the quality of the water leaving the treatment apparatus. When the sensor detects a drop in quality, regeneration is initiated.
The past efforts at increasing the flow rates through this type of control valve have been costly or have required the use of external devices connected to external power. The control valves disclosed in the '549 and '025 patents do not require external power. All valving within the valve is operated by water pressure.